[OpenAFS] pre-fetch cache

[Jeffrey Altman]

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Brian May wrote:
> On Mon, Jul 18, 2005 at 11:17:07PM -0400, Matthew Miller wrote:
> 
>>>I have considered this might be possible by setting up a cron job,
>>>perhaps with the help of reauth, that has read-only access to the
>>>required files. This cron job could do something like "cat file >
>>>/dev/null" for every file to force it to appear in the cache.
>>
>>Yep. :)
> 
> 
> I think I forgot to consider one important factor: The client will be
> Windows, not Linux/Unix.

cron jobs on windows are executed via the AT service.

> Me thinks this probably has just turned a simple cron job into a
> complicated mess, especially if you consider the user may not be logged
> in overnight.

the same would have been true on Unix/Linux.

> Oh well...
> 
> What would be nice is a special volume type that is a combination of the
> cache and replicated read-only volumes.  If the master copy of any file
> in this volume changes, then all replicated copies of this file are
> deleted, and the next request is forwarded to the master server. Write
> requests are forwarded to the master server. That way multiple clients
> at one site can "share" the one cache copy.

I don't understand how this would help share a cache.   The cache data
would still have to be read over the network.

Keep in mind that the Windows cache is now persistent.  You can cache
up to 1.3GB on the client.  So you only need to download the data once.
If you are planning on reading the same data repeatedly across numerous
reboots you might not need to precache as much as you think.

Jeffrey Altman



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